$primary: #01a0ff!default;
$white: #ffffff!default;
$second-text: #999!default;
$background: #f8f8f8!default;
$red: #ed4622!default;
@function second($i){
    @return $i * 0.5s
}
@mixin word($i) {
    .word#{$i}{
        opacity: 0;
        animation: word 1s forwards second($i);
    }
};
@for $i from 1 through 7 {
    @include word($i);
}

page{
    height: 100%;
    height: 100%;
    background:url('http://www.qinhanwen.xyz/background.jpeg') no-repeat;
    background-size:100% 100%; 
}